Systems, methods, and a kit for determining the presence of fluids

Abstract

This invention relates to nucleic-acid based product authentication and identification by determining authentication codes comprising target nucleic acids using oligonucleotide probes associated with samples. The presence of the authentication code is determined using detection methods, such as flow cytometric methods, capable of particle discrimination based on the light scattering or fluorescence properties of the particle. Target-correlated fluorescence signal, originating from a target nucleic acid hybridized to labeled complementary oligonucleotides is determined as an indicator of the presence of the authentication code. In some embodiments, an intercalating dye is used to determine the presence of target nucleotide/oligonucleotide heterodimers and identify an authentication code.

The invention claimed is: 
     
         1 . A method of constructing a nucleic acid sequence for use in authenticating a sample, the method comprising:
 randomly generating a plurality of nucleic acid sequences of a user-specified length;   comparing the plurality of nucleic acid sequences to known biological sequences; and   selecting the nucleic acid sequences having fewer than 10 alignments with the known biological sequences based on the comparison.   
     
     
         2 . The method of  claim 1 , further comprising incorporating at least one stop codon into each one of the plurality of nucleic acid sequences. 
     
     
         3 . The method of  claim 1 , further comprising incorporating at least one stop codon complement into each one of the plurality of nucleic acid sequences. 
     
     
         4 . The method of  claim 1 , further comprising:
 determining the length of the alignment between the nucleic acid sequence and the known biological sequence; and   excluding nucleic acid sequences exceeding a predetermined number of alignments with a known biological sequence, wherein the alignment exceeds a predetermined length.   
     
     
         5 . The method of  claim 1 , further comprising:
 determining a length of consecutive mononucleotide runs for each nucleotide in the nucleic acid sequence; and   excluding nucleic acid sequences having at least one consecutive mononucleotide run exceeding a predetermined length.   
     
     
         6 . The method of  claim 1 , further comprising:
 determining secondary structure for each of the plurality of nucleic acid sequences; and   excluding nucleic acid sequences having a number of secondary structures exceeding a predetermined number.   
     
     
         7 . The method of  claim 6 , wherein the secondary structure is selected from the group consisting of loops and pseudo knots.